F4U G Limits

[Toad]

I know there a few guys on this board that know just about everything about the Corsair.

I'm looking for the Flight Manual G limits.

I'd like to know the positive, negative, assymetric (rolling) limits.

I'd also like to know the "redline" airspeed (Vne). I'm not sure if the old WW2 data lists this like we do now (indicated airspeed to a certain altitude, above that in Mach) but any altitude correlations would also be appreciated.

Surely some of you Corsair Scholars has this stuff tucked away somewhere?

Thanks

[wells]

7.5 positive, 3.5 negative

With a centerline drop tank or 1000 lbs bomb, the positive limit is 5G's (same neg limit) and do not exceed 375 knts.

Full roll deflection is allowed up to 300 knts IAS.  At higher speeds, the use of ailerons should be limited to the same stick force as is required for full throw at 300 knots.

[Toad]

Thanks Wells!

I guess they gave no numerical assymetic limit then?

Going to be tough to figure "stick force" on a computer!

Any clean Vne mentioned?



[This message has been edited by Toad (edited 02-01-2000).]

[wells]

the chart for dive limits is missing from the manual I have.  says it will be added at a later date or something....

Yeah, dunno what the stick force is at 300 knts, but it looks like it's pretty light and that the pilot could exceed the limits beyond 300 knts if he wasn't careful.  

With the twin pylons, there were no special limits.  The normal limits applied.

[funked]

Keep in mind there is a 1.5 factor of safety (usually) on those limits.

[wells]

From AHT,

At 30000' they were restricted to 260 knts IAS corresponding to Mach 0.72; at 20000', it was 320 knts IAS, at 10000', it was 385 knts (443 mph IAS) for 3.5 g's (Mach 0.70) and 350 knts IAS for a 6.5 G pullout (Mach 0.63).

[Toad]

Wells, good stuff..thx!

So, if I'm 10K or below I should probably be graying/blacking out before I bend the tin.

At least in a "straight pull"...that 300kt stickforce thing has got me to REALLY wondering about their assymetric limit.

It would be pretty easy to pull hard and roll in combat with your fangs out and hair on fire.

Still, if it was a big problem you'd think there'd be lots of warstories about it floating around.

[Pyro]

Ronni put up some new plane write-ups in the help section today that has all that technical stuff in there.



------------------
Doug "Pyro" Balmos
HiTech Creations

"If it's stupid but works, it's not stupid."

[Pyro]

Wells, the reason for not using full deflection on the ailerons past that speed is that they would overbalance.



------------------
Doug "Pyro" Balmos
HiTech Creations

"If it's stupid but works, it's not stupid."

[funked]

"Still, if it was a big problem you'd think there'd be lots of warstories about it floating around."

Maybe not - if you encountered the problem you probably wouldn't be around to tell stories.  

[Bradburger]

I was reading an article by the late Mark Hanna on displaying the Corsair a while back and remember him saying that one had to be careful with regard to the amount of aileron input used at speeds above 300mph.

It seems that if you apply full deflection (easily done)you run the risk of damaging or at worst destroying the plywood covered ailerons.

Now if only AH would model this!

Cheers

Bradburger




[This message has been edited by Bradburger (edited 02-02-2000).]

[F4UDOA]

Actually I have made several post in this board regard the weak structural limitations on the F4U G capabilities in AH. The F4U was one of the strongest structural A/C in WW2.
I have read of pilots reading 11g's without wing failure. In fact I have never read of a wing failure of an F4U in combat or testing.
However I have lost my wing with little or few g's at high speed i.e. 450IAS in AH
In fact the Corsair was rated as second best ailerons at 350mph to the Mustang and second at 100Mph to the Hellcat. Also it was rated as best in stabilty and control in a dive which gives merit to the fact that the airframe was used to deliver such large payloads in a dive at high speed. Such as two
TinyTim 11.5 inch rockets. I don't think this A/C should be losing wings in a high speed dive under almost any G conditions while unloaded. It certainly could withstand a higher G load than a consious pilot anyway.

 F4UDOA
(Insert slogan here)

[wells]

Since the whole center section spar of the wing is built as one piece, it should be strong as hell, like only a severe crash would break it!  The only real threat of losing a wing would occur at the folding joint.

Doing a few stress calculations...

If the wing joint were in the center or at the fuselage, it would be required to support 450000 lbs.ft of torque on it at 7.5G with a 50% safety margin (failure at 11 G).  The joint where the wing folds only needs to support 112500 lbs.ft at 7.5G's.  

I believe the Zero also had a one piece wing spar!

[Toad]

Funked, unlike what we do here, the military probably didn't run around too much as "lone eagles."

In combat and in training they flew as flights (sections to you Navy pukes) or entire squadrons.

Somebody would have seen something if it happened often enough.

[funked]

Toad, yes I'm pretty familiar with WW2 fighter ops, but you must admit my observation has some merit.  One of the first uses of telemetry was to determine the cause of empennage failure on the Typhoon.  Nobody had lived to describe the problem, so they instrumented a test article in case the driver didn't make it back.

From what I've read, the restriction on aileron deflection in the F4U could be (and was) ignored.

Seems likely that it was similar to the engine restrictions in that it was based on fatigue life not on yield strength.  I.e. it won't break anything the first time you do it, but doing it repeatedly will decrease the life of some components.

However I have not read extensively on this particular problem with the F4U.

[This message has been edited by funked (edited 02-02-2000).]